Increasing Pahi 31 by 10%

I am looking at maybe building a Pahi 31, I would like to know if somone increase the dimension by 10%?

Basically I want to increase all the dimension of the boat by 10% to make just a little bigger execpt the overall beam of 16 foot that i would like to keep the same. I understand that by doing thus will increase the displacement by 33%.

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Changes such as you are proposing create exponential changes that you cannot fathom unless you have done it before.

It still can catch me off guard when I make a small change to something, then further into the build I find a problem caused by the change. Solving the problem results in more change, which shows up as another problem later that must be solved, and the cycle continues.

What you propose could add double the labor required unless you are capable of seeing the ramifications all the way through the build process BEFORE you start.

Why not just build a Tangaroa MKIV with the addition of Tiki style beams. It is a pretty simple build if you keep changes to a minimum, has standing headroom, and is a great sailor. Sure it is over 16' beam, but marina life gets expensive quickly. Learn anchoring, or pick up a mooring to save money.

Tangora MKIV seams to be a good option! It is right between in size of the Tiki 38 and the Pahi 31. But I love the look of the Pahi. Also It seams that over 16 foot beam Marina start to charge for two spot! I understand that Marina becomes expensive but in my situation with very young children and a wife It as to be easy otherwise I will be sailing alone!!!!

I also think that the Pahi might sail better to windward with the daggerboard than the Tangora. I also like the round V shape of the Pahi that gives you a little volume in the hull shape. Anyway the best would be to go try those two catamaran to make a decision.

I am still studying and it seams that if I just scale all the dimension by 10% it should be reasonable. Now the question: Is it a modification to scale it up?

There is one here in NZ called Soltice. She is a Pahi 31 scaled up 10%, turned into a 34 footer, not sure of the beam. Was for sale for a while a couple of years back, I had a look at her and went for a sail. She sailed well. She was about 20 years old so certainly stood the test of time. She had quite a good centre pod too.

Didn't take it any further but only because I thought he was asking a bit too much, ended up with my Tiki 26.

I remember the price dropped quite a bit on that one when it was for sale in Auckland, down to about 15000 which was looking pretty cheap, saw it more recently in Tauranga and for sale again about a year ago. I think Don brazier ? who has put up storm tactics on here and was the NZ Wharram agent may recall original owner/builder?

I lived on a Tiki 30 with my wife (at the time) and our two kids ages 1 and 3. In the seven months we lived aboard we were at a dock exactly 1 day, which was the day we moved aboard. We moved down from a 43' Colvin Gazelle. On that boat we spent one month at a dock two times in three years, both when our children were born. Before that we lived on a Tangaroa MKIV and spent 1 day at a dock in three years.

From experience, a Tiki 30 is too small for a family to live on long term, which is why it was sold. A Pahi 31 is not going to be any better, even if stretched 10% (IF your idea is to scale up the Pahi 31 proportionally in all dimensions, that is definitely a significant modification that I would never wish to do, and I have built a T30, T38, and am building a Narai MKIV.)

If your wife has reservations about living on a boat with her children, and fears for her children's safety, welcome to the club. I would recommend that before you embark on what could be a very long and expensive build just to avoid anchoring out, that you convince your wife to read about other women who have lived with their families on boats.

The right mindset and education about the subject will pay off long before anything else.

Tangora MKIV seams to be a good option! It is right between in size of the Tiki 38 and the Pahi 31. But I love the look of the Pahi. Also It seams that over 16 foot beam Marina start to charge for two spot! I understand that Marina becomes expensive but in my situation with very young children and a wife It as to be easy otherwise I will be sailing alone!!!!

I also think that the Pahi might sail better to windward with the daggerboard than the Tangora. I also like the round V shape of the Pahi that gives you a little volume in the hull shape. Anyway the best would be to go try those two catamaran to make a decision.

I am still studying and it seams that if I just scale all the dimension by 10% it should be reasonable. Now the question: Is it a modification to scale it up?

As an exercise, I find the idea very compelling, but from a practical point of view there are some pitfalls.

If we were just stretching her three feet in length, adding an additional bulkhead amidships would probably be all that was needed. The increase in all directions means the hull will need to be lofted and every structural part redrawn, and possibly resized. The good news is, the Pahi 31 hull is fairly straight amidships and the bow and stern are symmetrical. The bad news is, as Budget Boater pointed out, the nuances may bite you in the ass. The Pahi 31 is a 40 year old design originally constructed utilizing resorcinol glues and polyester resins. While the structure appears to be over-engineered for epoxy, only JWD can tell you for sure, and this is the kind of answer you want to pay for. An "OK" in an email isn't going to cut it. The plywood skin, structural members (scantlings), and gluing schedule may need to be scaled up.

Boatsmith (David) is enthusiastic because, before he got side tracked to his Arriki builds (look, a squirrel!), he had a stretched Tiki 30 in the works. He's already gone through the thought process and has sufficient experience to know where the problems lie.

Which leaves you with four options:

1. Pay someone like David to build the boat and let him work out the details.2. Pay JWD for a design change, and then execute their modified design.3. Figure out the design changes on your own and build the boat.4. Go with a different JWD design.

Where you go depends on what you are trying to achieve. I prefer working wood and to me, building the boat is as important as eventually sailing the boat. So, my preference is to work out any design changes and then get approval from the designer. I may lengthen my Pahi 31 by three feet, just because. You may have different priorities.